This invention relates to incandescent lamps, and more particularly, to a baseless incandescent lamp wherein complementary mating to an electrical socket is accomplished by threads formed in the incandescent lamp itself.
Incandescent lamps are well-known for providing pleasing illumination and finding applications in millions of homes having existing complementary screw-like sockets for the incandescent lamp. The manufacturers of incandescent lamps, because of the vast quantities produced, are constantly seeking means for reducing the cost of the incandescent lamp itself.
One of the ways of reducing the cost of the incandescent lamp is to eliminate the electrically conductive base of the lamp. Although contributing to the cost of the lamp, the electrical base of the incandescent lamp helps to provide for a well-defined electrical operation of the incandescent filament of the lamp itself. The electrical base formed of metal and having a screw-like arrangement provides for metal-to-metal contact between the base and the socket and thereby good electrical contact for the electrical operation of the incandescent filament of the lamp. The metal base of the incandescent lamp, although having its desired electrical characteristic, is still a cost contributor and it is economically desirable to eliminate the metal base and provide other electrical means for the baseless incandescent lamp to mate with the complementary electrical socket.
An incandescent lamp having an electrically conductive base reduced in size is described in Japanese Utility Model No. 53-20 918 (1.6.78) of Goshi-Kaisha Naka Denki Seisakusho. The Japanese incandescent lamp has a male-threaded portion formed of glass for mating with the female-threaded portion of an electrical socket and integrated with the glass of the incandescent lamp itself. The incandescent lamp has a ring-shaped contact portion located on its lower portion for providing the electrical contact of the incandescent filament with the electrical socket.
It is considered desirable that a baseless incandescent lamp be provided in which the electrical conductive base be further reduced in size and complexity by appropriate means to further reduce the cost and simplify the fabrication both of the lamp while still providing for proper operation of its incandescent filament.
Accordingly, an object of the present invention is to provide a baseless incandescent lamp having electrical means for complementary mating with the electrical socket and which means provides for good electrical contact and proper operation of the incandescent filament.